Natural language expression in response to a query

ABSTRACT

Methods and apparatus, including computer products, for generating a natural language expression in response to a query. A computer-implemented method of generating a natural language expression in response to a query, includes generating a text frame from the query, and processing the text frame in conjunction with a grammar and one or more logic configuration files applied recursively to the text frame to generate the natural language expression from the query, the logic configuration files including functions that can pass arguments.

CROSS REFERENCES TO RELATED APPLICATIONS

This application is a continuation (and claims the benefit of priorityunder 35 USC 120) of U.S. application Ser. No. 10/704,225, filed Nov. 6,2003, which is a continuation of U.S. application Ser. No. 09/562,539,filed May 2, 2000. The disclosures of the prior applications areconsidered part of (and are incorporated by reference in) the disclosureof this application.

BACKGROUND

The present invention relates to data processing by digital computer,and more particularly to generating a natural language in response to aquery.

A search engine is a software program used for search and retrieval indatabase systems. The search engine often determines the searchingcapabilities available to a user. A web search engine is often aninteractive tool to help people locate information available over theworld wide web (WWW). Web search engines are actually databases thatcontain references to thousands of resources. There are many searchengines available on the web, from companies such as Alta Vista, Yahoo,Northern Light and Lycos.

SUMMARY

The present invention provides methods and apparatus, including computerprogram products, for generating a natural language expression inresponse to a query.

In an aspect, the invention features a computer-implemented method ofgenerating a natural language expression in response to a query,including generating a text frame from the query, and processing thetext frame in conjunction with a grammar and one or more logicconfiguration files applied recursively to the text frame to generatethe natural language expression from the query, the logic configurationfiles including functions that can pass arguments.

In embodiments, the method can include matching the natural languageexpression to content residing in a database. The database can reside ina server in a network.

The matched content can be a search result summary. The text frame caninclude a data structure, the data structure representing an expandedquery, the expanded query representing different elements of the queryand different criteria of the query. The data structure can includerows, each of the rows having a key, the key identifying information ineach of the rows. The data structure further can include a plurality ofdata structures. The grammar can include natural language rules.

Generating the text frame further can include encapsulating theprocessed text frame in a markup language. The markup language can beextensible markup language (XML). The markup language can be hypertextmarkup language (HTML).

In another aspect, the invention features a computer-implemented methodof processing a query including generating a text frame for the query,loading a grammar and one or more logic configuration files, andprocessing the text frame in conjunction with the grammar and the one ormore logic configuration files to generate a natural language expressionfrom the query.

In embodiments, the method can include matching the natural languageexpression to content residing in a database. The database can reside ina server in a network.

Matched content can be a search result summary. The text frame caninclude a data structure, the data structure representing an expandedquery, the expanded query representing different elements of the queryand different criteria of the query. The data structure can includerows, each of the rows having a key, the key identifying information ineach of the rows. The data structure can include a plurality of datastructures. The grammar can include natural language rules.

Generating the text frame further can include encapsulating theprocessed text frame in a markup language.

Other features and advantages of the invention are apparent from thefollowing description, and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a network configuration.

FIG. 1A is a flow diagram of a search process.

FIG. 2 is a flow diagram of an information access process.

FIG. 3 is a flow diagram of a meaning resolution process used by theinformation access process of FIG. 2.

FIG. 4 is a block diagram of an information interface.

FIG. 5 is a flow diagram of a reduction and summarization process usedby the information access process of FIG. 2.

FIG. 6 is a flow diagram of a prose process used by the informationaccess process of FIG. 2.

FIG. 7 is flow diagram of a bootstrap process used by the informationaccess process of FIG. 2.

FIG. 8 is flow diagram of a database aliasing process used by theinformation access process of FIG. 2.

FIG. 9 is flow diagram of a database aliasing file generation processused by the information access process of FIG. 2.

FIG. 10 is a flow diagram of a query expansion process used by theinformation access process of FIG. 2.

Like reference numbers and designations in the various drawings indicatelike

DETAILED DESCRIPTION

Referring to FIG. 1, a network configuration 2 for executing aninformation access process includes a user computer 4 connected via alink 6 to an Internet 8. The link 6 may be a telephone line or someother connection to the Internet 8, such as a high speed T1 line. Thenetwork configuration 2 further includes a link 10 from the Internet 8to a client system 12. The client system 12 is a computer system havingat least a central processing unit (CPU) 14, a memory (MEM) 16, and alink 18 connected to a storage device 20. The storage device 20 includesa database 21, which contains information that a user may query. Theclient system 12 is also shown to include a link 22 connecting theclient system 12 to a server 24. The server 24 includes at least a CPU25 and a memory 26. A plug-in 27 is shown resident in the memory 26 ofthe server 24. The plug-in 27 is an application program module thatallows a web site code running on the client system 12 to execute aninformation access process residing in the memory 26 of the server 24.The plug-in 27 allows the web site application to incorporate resultsreturned from the information access process while it is generating HTMLfor display to the user's browser (not shown). HTML refers to HypertextMarkup Language and is the set of “markup” symbols or codes inserted ina file intended for display on a World Wide Web browser. The markuptells the Web browser how to display a Web page's words and images forthe user. The individual markup codes are referred to as elements (alsoreferred to as tags). As is shown, the server 24 shares access to thedatabase 21 on the storage device 20 via a link 28. Other networkconfigurations are possible. For example, a particular networkconfiguration includes the server 24 maintaining a local copy of thedatabase 21. Another network configuration includes the Internet 8connecting the client system 12 to the server 24.

Referring to FIG. 1A, a search process 30 residing on a computer systemincludes a user using a web-browser on a computer connecting 32 to theInternet and accessing a client system. Other embodiments include adirect connection from the user computer to the client system. Theclient system displays 33 a page on the web browser of the user and theuser inputs 34 a query in a query input box of the displayed page. Thequery is sent 35 to an information access process residing on a serverfor processing. The information access process processes 36 the queryand sends the results to the client system. The results are thendisplayed 37 to the user.

Referring to FIG. 2, an information access process 40 on a computersystem receives 42 a query by a user. The query may be a word ormultiple words, sentence fragments, a complete sentence, and may containpunctuation. The query is normalized 44 as pretext. Normalizationincludes checking the text for spelling and proper separation. Alanguage lexicon is also consulted during normalization. The languagelexicon specifies a large list of words along with their normalizedforms. The normalized forms typically include word stems only, that is,the suffixes are removed from the words. For example, the word“computers” would have the normalized form “computer” with the pluralsuffix removed. The normalized text is parsed 46, converting thenormalized text into fragments adapted for further processing.Annotating words as putative keys and values, according to a featurelexicon, produces fragments. The feature lexicon is a vocabulary, orbook containing an alphabetical arrangement of the words in a languageor of a considerable number of them, with the definition of each; adictionary. For example, the feature lexicon may specify that the term“Compaq.RTM.” is a potential value and that “CPU speed” is a potentialkey. Multiple annotations are possible.

The fragments are inflated 48 by the context in which the text Inputtedby the user arrived, e.g., a previous query, if any, that was inputtedand/or a content of a web page in which the user text was entered. Theinflation is preformed by selectively merging 50 state informationprovided by a session service with a meaning representation for thecurrent query. The selective merging is configurable based on rules thatspecify which pieces of state information from the session serviceshould be merged into the current meaning representation and whichpieces should be overridden or masked by the current meaningrepresentation.

The session service stores all of the “conversations” that occur at anygiven moment during all of the user's session. State information isstored in the session service providing a method of balancing load withadditional computer configurations. Load balancing may send each userquery to a different configuration of the computer system. However,since query processing requires state information, storage of stationinformation on the computer system will not be compatible with loadbalancing. Hence, use of the session service provides easy expansion bythe addition of computer systems, with load sharing among the systems tosupport more users.

The state information includes user specified constraints that were usedin a previous query, along with a list of features displayed by theprocess 40 and the web page presented by the main server. The stateinformation may optionally include a result set, either in its entiretyor in condensed form, from the previous query to speed up subsequentprocessing in context. The session service may reside in one computersystem, or include multiple computer systems. When multiple computersystems are employed, the state information may be assigned to a singlecomputer system or replicated across more than one computer system.

Referring now to FIG. 3, the inflated sentence fragments are converted52 into meaning representation by making multiple passes through ameaning resolution process 70. The meaning resolution process 70determines 72 if there is a valid interpretation within the text queryof a key-value grouping of the fragment. If there is a validinterpretation, the key value grouping is used 74. For example, if theinput text, i.e., inflated sentence fragment, contains the string “500MHz CPU speed,” which may be parsed into two fragments, “500 MHz” valueand “CPU speed” key, then there is a valid grouping of key=“CPU speed”and value=“500 MHz”.

If no valid interpretation exists, a determination 76 is made on whetherthe main database contains a valid interpretation. If there is a validinterpretation in the main database, the key value group is used 74. Ifno valid interpretation is found in the main database, the process 70determines 78 whether previous index fields have a high confidence ofuniquely containing the fragment. If so, the key value grouping is used74. If not, other information sources are searched 80 and a valid keyvalue group generated 82. If a high confidence and valid putative key isdetermined through one of the information sources consulted, then thegrouping of the key and value form an atomic element are used 74. Tomake it possible to override false interpretations, a configuration ofgrammar can also specify manual groupings of keys and values that takeprecedence over the meaning resolution process 70.

Referring again to FIG. 2, meaning resolved fragments, representing theuser query, are answered 54. In providing an answer or answers, logicmay decide whether or not to go out to the main database, whether or notto do a simple key word search, or whether or not to do directnavigation, and so forth. Answer or answers are summarized and organized56. Summarization and organization may involve intelligent discarding ofexcessive and unneeded details to provide more meaningful results inresponse to the user query.

When a user asks a question, i.e., submits a query, there is usually noway to predict how many appropriate results will be found. The process40 attempts to present the user with no more information than can bereasonably absorbed. This is often dictated by the amount of spaceavailable on the users displayed web page.

Prose is generated 58. The prose represents the specific query the userinitially asked, followed by organized and summarized results to theuser query. The prose and organized answers are outputted 60 to the userfor display. Output to the user may involve producing HTML of the proseand organized answers and/or XML for transmission of the organizedanswers and dynamic prose back to the main server for HTML rendering.XML refers to extensive markup language, a flexible way to providecommon information formats and share both the format and the data on theword wide web, intranets, and elsewhere. Any individual or group ofindividuals or companies that wants to share information in a consistentway can use XML.

Referring to FIG. 4, the control logic of process 40 includes aninformation interface 80. The purpose of the information interface 80 isto isolate the control logic from the details of any given web site onthe main server or other servers, e.g., how they store particularinformation. For example, different web sites will name thingsdifferently and/or store things differently. The information interface80 provides a standard format for both receiving information from, andsending information to, the control logic of process 40, and normalizesthe interface to various information sources. The information interface80 includes an information retrieval process 82, a database (db)aliasing process 84, a URL driver process 86 and a storage process 88.

An exemplary illustration of a standard format used by the informationinterface 80 is shown as follows: {_(—) :features {features :_ {feature:key ‘product price‘} :_ {feature :key ‘product min age‘} :_ {feature:key ‘product max age‘} :_ {feature :key ‘product name‘} :_ {feature:key ‘sku‘} } :constraints {or :_ {and :_ {feature :key ‘productdescription‘ :value {or :_ {value eq: ‘fire trucks′ :kwid ‘fire trucks‘}} } } } :sort {features :_ {feature :key ‘product price‘} :_ {feature:key ‘product min age‘} :_ {feature :key ‘product max age‘} :_ {feature:key ‘product name‘} :_ {feature :key ‘sku‘} } }

The information interface 80 handles and formats both “hard” and “soft”searches. A hard search typically involves a very specific query forinformation, while a soft search typically involves a very general queryfor information. For example, a hard search may be for the price to beless than $500 where price is a known column in the database andcontains numeric values. The IR engine to include occurrences of “firetruck” within textual descriptions may interpret a soft search for “fireengine”.

The URL driver process 86 maintains a URL configuration file. The URLconfiguration file stores every detail of a web site in compressedformat. The compression collapses a set of web pages with the same basictemplate into one entry in the URL configuration file. By way ofexample, the following is a sample portion of a URL configuration fileentry: /newcar/$Manufacturer/$Year/$Model/keys: overview/newcar/$Manufacturer/$Year/$Model/safetyandreliability. asp keys:safety reliability

The db aliasing process 84 handles multiple words that refer to the sameinformation. For example, the db aliasing process 84 will equate“laptop” and “notebook” computers and “pc” and “personal computer.”

The URL driver process 86 includes bidirectional search logic forinteracting with the URL configuration file. In a “forward” searchdirection, a specific query is received and the search logic searchesthe URL configuration file for a best match or matches and assigns ascore to the match or matches, the score representing a relative degreeof success in the match. The score is determined by the number of keysin the URL configuration entry that match the keys desired by thecurrent meaning representation of the query. More matching keys willresult in a higher score.

In a “reverse” direction, the search logic contained within the URLdriver process 86 responds to a query by looking at the contents of theweb page in which the user is currently viewing and finds the answer tothe new user query in combination with the features of the web pagewhich the user is viewing, along with a score of the match or matches.Thus, the search logic of the URL driver process 86 looks at the currentweb page and connects current web page content with current userqueries, thus deriving contacts from the previous line of questioning.

As described with reference to FIG. 2, the information access process 40contains control logic to provide answers to a user's query. The answersare summarized and organized. Typically, the results of a specificdatabase search, i.e., user query, will identify many rows of results.These rows will often result in more than one web page of displayedresults if the total result is taken into account. The informationaccess process 40 reduces the number of rows of answers in an iterativefashion.

Referring to FIG. 5, a reduction and summarization process 110determines 112 a count of the total number of results obtained fromsearching the main database. The reduction and summarization process 110determines 114 the amount of available space on the web page for displayof the answers. A determination 116 is made as to whether the number ofresults exceeds the available space on the web page. If the number ofresults does not exceed the available space on the web page the resultsare displayed 118 on the web page. If the number of results exceedsavailable space on the web page, a row of results is eliminated 120 toproduce a subset of the overall results. The number of results containedwithin the subset is determined 122. The determination 116 of whetherthe number of results contained within the subset exceeds availablespace on the web page is executed. The reduction and summarizationprocess 110 continues until the number of results does not exceedavailable display space on the web page.

When a reduction of results is made, the reduction and summarizationprocess 110 has no prior knowledge of how it will affect the totalcount, i.e., how many rows of data will be eliminated. Reductions mayreduce the overall result count, i.e., rows of result data, in differentways. Before any reduction and summarization is displayed in tabularform to the user, the resultant data is placed in a hierarchical treestructure based on its taxonomy. Some searches will generate balancedtrees, while others will generate unbalanced trees. Further, some treeswill need to be combined with other trees. To reduce the resultant data,the reduction and summarization process 110 looks at the lowest membersof the tree, i.e., the leaves, and first eliminates this resultant data.This results in eliminating one or more rows of data and the overallcount of resultant data. If the overall count is still too large, thereduction and summarization process 110 repeats itself and eliminatesanother set of leaves.

Eliminating rows (i.e., leaves) to generate a reduced result set ofanswers allows the reduction and summarization process 110 to reduceidentical information but maintain characterization under identicalinformation in the hierarchical tree structure. The identical rowsrepresenting identical information can be collapsed. For example, if theeliminated row in the reduced result set contains specific priceinformation, collapsing the eliminated row may generate price rangesinstead of individual prices.

As mentioned previously, some results may generate multiple trees. In aparticular embodiment, to reduce the overall amount of resultant data inthe result set, information is eliminated where the greatest number ofleaves is present across multiple trees.

Referring again to FIG. 2, it should be noted that sometimes theinformation access process 40 will provide no summarization and/orreduction of results, e.g., the user asks for no summarization or theresults are very small. Organization of resultant data generally putsthe answers to the user's query into a hierarchy, like a table, forexample, and the table may include links to other web pages for displayto the user. Links, i.e., addresses associated with each row of thedisplayed results, are encoded within each element of the hierarchicaltree structure so that the user may navigate to a specific web page byclicking on any of the links of the resultant rows of displayed data.The encoding is done by including a reference to a specific session knowby the session service along with the address to an element in the tableof results displayed during the specific session. State informationprovided by the session service can uniquely regenerate the table ofresults. The address is a specification of the headings in the table ofresults.

For example, if an element in the hierarchical structure is under asubheading “3” which is under a major heading “E” the address wouldspecify that the major heading is “E” and that the subheading is “3.”Response planning may also include navigation to a web page in which theuser will find a suitable answer to their query. As previouslydescribed, prose is generated and added to the results.

Referring to FIG. 6, a prose process 140 includes receiving 142 thenormalized text query. The normalized text query is converted 144 toprose and the prose displayed 146 to the user in conjunction with theresults of the user query.

The prose process 140 receives the normalized text query as a textframe. The text frame is a recursive data structure containing one ormore rows of information, each having a key that identifies theinformation. When the text frame is passed to the prose process 140 itis processed in conjunction with a prose configuration file. The proseconfiguration file contains a set of rules that are applied recursivelyto the text frame. These rules include grammar having variablescontained within. The values of the variables come from the text frame,so when combined with the grammar, prose is generated. For example, onerule may be “there are $n products with $product.” The variables $n and$product are assigned values from an analysis of the text frame. Thetext frame may indicate $n=30 and $product=leather. Thus, the prose thatresults in being displayed to the user is “there are 30 products withleather.”

More than one rule in the prose configuration file may match the textframe. In such a case, prose process 140 will recursively build anappropriate prose output. In addition, if two rules in the proseconfiguration file match identically, the prose process 140 mayarbitrarily select one of the two rules, but the database can beweighted to favor one rule over another. In some cases, default rulesmay apply. In addition, some applications may skip over keys and may userules more than once.

The prose configuration file also contains standard functions, such as afunction to capitalize all the letters in a title. Other functionscontained within the prose configuration may pass arguments.

The information access process 40 (of FIG. 2) interfaces with a numberof configuration files in addition to the prose configuration file.These configuration files aid the information access process 40 inprocessing queries with the most current data contained in the mainserver database. For example, the information access process 40 has abootstrapping ability to manage changes to a web page of the main serverand to the main server database. This bootstrapping ability is needed sothat when the main server database changes occur, the information accessprocess 40 utilizes the most current files.

The information access process 40 also includes a number of tools thatanalyze the main server database and build initial versions of all ofthe configuration files, like the prose configuration file; this isgenerally referred to as bootstrapping, as described above.Bootstrapping gives the information access process 40 “genuine”knowledge of how grammar rules for items searching looks like, specificto the main server database being analyzed.

Referring to FIG. 7, a bootstrap process 170 extracts 172 all textcorresponding to keys and values from the main server database. Theextracted text is placed 174 into a feature lexicon. A language lexiconis updated 176 using a general stemming process. Grammar files areaugmented 178 from the extracted keys and values. Generic grammar filesand previously built application-specific grammar files are consulted180 for rule patterns, that are expanded 182 with the newly extractedkeys and values to comprise a full set of automatically generatedgrammar files.

For example, if an application-specific grammar file specifies that“Macintosh” and “Mac” parse to the same value, any extracted valuescontaining “Macintosh.RTM.” or “Mac.RTM.” will be automatically convertinto a rule containing both “Macintosh” and “Mac.” The structuring ofthe set of grammar files into generic, application-specific andsite-specific files allows for maximum automatic generation of newgrammar files from the main server database. The bootstrapping process170 can build the logic and prose configuration files provided that asystem developer has inputted information about the hierarchy ofproducts covered in the main server database.

The hierarchy for a books database, for example, may include a top-leveldivision into “fiction” and “nonfiction.” Within fiction, the variousliterary genres might form the next level or subdivision, and so forth.With knowledge of this hierarchy, the bootstrapping process 170configures the logic files through link linguistic concepts relating toentries in the hierarchy with products in the main server database, sothat the logic is configured to recognize, for example, that “fiction”refers to all fiction books in the books database. The logicconfiguration files are also automatically configured by default, andsummarization and organization of the results uses all levels of thehierarchy. The prose configuration files are automatically generatedwith rules specifying that an output including, for example, mysterynovels, should include the category term “mystery novels” from thehierarchy. The bootstrapping process 170 may also “spider” 184 a mainserver database so as to build a language lexicon of the site, e.g.,words of interest at the site. This helps building robust configurationfiles. Spidering refers to the process of having a program automaticallydownload one or more web pages, further downloading additional pagesreferenced in the first set of pages, and repeating this cycle until nofurther pages are referenced or until the control specification dictatesthat the further pages should now be downloaded. Once downloaded,further processing is typically performed on the pages. Specifically,the further processing here involves extracting terms appearing on thepage to build a lexicon.

When the bootstrapping process 170 executes after original configurationfiles have been generated, the original configuration files are comparedwith the current configuration files and changes added incrementally asupdates to the original configuration files.

Referring again to FIG. 3, the information interface 80 includes thedatabase aliasing process 88. The database aliasing process 88 providesa method to infer results when no direct match occurs. Referring to FIG.8, a database (db) aliasing process 200 includes generating 202 andaliasing the file, and applying 204 the aliasing file to a user query.The automatic generation of the database aliasing file reduces theamount of initial development effort as well as the amount of ongoingmaintenance when the main server database content changes.

Referring to FIG. 9, a database aliasing file generating process 220includes extracting 222 names from the main server database. Theextracted names are normalized 224. The normalized names are parsed 226.The language lexicon is applied 228 to the normalized parsed names. Adetermination 230 is made on whether multiple normalized names map toany single concept. If so, alias entries are stored 232 in the databasealiasing file. In this manner, the grammar for the parser can beleveraged to produce the database aliasing file. This reduces the needfor the system developer to input synonym information in multipleconfiguration files and also allows imprecise aliases, which areproperly understood by the parser, to be discovered without any directmanual entry.

The db aliasing file, like many of the configuration files, is generatedautomatically, as described with reference to FIG. 9. It can also bemanually updated when the context of the database under investigationchanges. The database aliasing file is loaded and applied in such a wayas to shield its operations from the information interface 80 of FIG. 3.

In a particular embodiment, the application of the db aliasing file to aquery can be used in two directions. More specifically, in a forwarddirection, when a user query is received, applying the database aliasingfile to the user query and resolving variations of spelling,capitalization, and abbreviations, normalized the user query, so that anormalize query can be used to search the main server database. In areverse direction, if more than one alias is found, the search resultswill normalize on a single name for one item rather than all possiblealiases found in the main server database file.

Referring again to FIG. 4, the information interface 80 includes theinformation retrieval (IR) process 82. The information retrieval process82 purpose is to take a collection of documents on a main serverdatabase containing words, generate an inverse index known as an IRindex, and use the IR index to produce answers to a user query. Theinformation access process 40 (of FIG. 2) leverages grammar it developsfor front end processing when building the IR index to generate phasedsynonyms (or phrased aliases) for the document. More specifically, theinformation access process 40 applies the parser and grammar rules tothe document before the IR index is built. The effect of this can bedescribed by way of example. One rule may indicate the entity “laptop”goes to “laptop” or “notebook.” Thus, during parsing, if “notebook” isfound, it will be replaced by the entity “laptop,” which then getsrolled into the IR index.

At search time, the information access process 40 attempts to finddocuments containing the search terms of the user query, and inaddition, the incoming user search terms are run through the parser,that will find multiple entities, if they exist, of the same term. Thus,combining the parser and the grammar rules, the information accessprocess 40 maps a user query into its canonical form of referring to theitem.

The information retrieval process 40 may also process a grammar andgenerate a grammar index, which can help find other phrased synonymsthat other methods might not find. For example, “Xeon”, an IntelMicroprocessor whose full designation is the “Intel Pentium.RTM. XeonProcessor,” may be represented in canonical form as “Intel XeonProcessor.” If a user query is received for “Intel,” “Xeon” would not befound without the grammar index of the information access process 40will search the grammar index and produce a list of all grammar tokenscontaining “Intel,” and add this list to the overall search so that theresults would pick up “Xeon,” among others. The use of the parser andgrammar rules to specify the expansion of a full user query to includesynonyms allows for centralization of linguistic knowledge within thegrammar rules, removing a need for additional manual configuration togain the query expansion functionality.

Referring to FIG. 10, a query expansion process 250 includes normalizing252 and parsing 254 the putative text. The canonical non-terminalrepresentations are inserted 256 into an IR index in place of the actualputative text.

In an embodiment, the punitive text is used “as-is.” However, when auser requests a search, the putative search phrase is processedaccording to the grammar rules to obtain a canonical non-terminalrepresentation. The grammar rules are then used in a generative mannerto determine which other possible phrases could have generated the samecanonical non-terminal representation. Those phrases are stored in theIR index.

The “as-is” method described above is generally slower and less completein query expansion coverage, because it may take too long to generateall possible phrases that reduce to the same canonical non-terminalrepresentation, so a truncation of the possible phrase list can occur.However, the “as-is” method has the advantage of not requiringre-indexing the original text whenever the grammar rules are updated.

In a particular embodiment, the information access process 40 (of FIG.2) combines an IR index search with a main server database search torespond to queries that involve a combination of structured featuresstored in a database (e.g., price, color) and unstructured informationexisting in free text. Structured Query Language (SQL) is used tointerface to a standard relational database management system (RDBMS).To jointly search an RDBMS and an IR index, the information accessprocess 40 issues an unstructured search request to the IR index, usesthe results, and issues a SQL query that includes a restriction to thoseinitial IR index search results. However, the free text information inthe IR index may not always correspond to individual records in theRDBMS. In general, there may be many items in the IR index thatcorrespond to categories of items in the RDBMS. In order to improve theefficiency of searches involving such items in the IR index, the IRindex is further augmented with category hierarchy information. Thus, amatch to an item in the IR index will also retrieve correspondingcategory hierarchy information, which can then be mapped to multipleitems in the RDBMS.

The information access process 40 parser contains the capability ofprocessing large and ambiguous grammar efficiently by using a graphrather than “pure” words. The parser allows the information accessprocess 40 to take the grammar file and an incoming query and determinethe query's structure. Generally, the parser pre-compiles the grammarinto a binary format. The parser then accepts a query as input text,processes the query, and outputs a graph.

LR parsing is currently one of the most popular parsing techniques forcontext-free grammars. LR parsing is generally referred to as“bottom-up” because it tries to construct a parse tree for an inputstring beginning at the leaves (the bottom) and working towards the root(top). The LR parser scans the input string from left to right andconstructs a right most derivation in reverse.

The information access process 40 improves on the LR parser by addingthe ability to handle ambiguous grammars efficiently and by permittingthe system developer to include regular expressions on the right handside of grammar rules. In the “standard” LR parser, an ambiguous grammarwould produce a conflict during the generation of LR tables. Anambiguous grammar is one that can interpret the same sequence of wordsas two or more different parse trees. Regular expressions are commonlyused to represent patterns of alternative and/or optional words. Forexample, a regular expression “(a.vertline.b)c+” means one or moreoccurrences of the letter “c” following either the letter “a” or theletter “b.”

In traditional LR parsing, a state machine, typically represented as aset of states along with transitions between the states, is usedtogether with a last-in first-out (LIFO) stack. The state machine isdeterministic, that is, the top symbol on the stack combined with thecurrent state specifies conclusively what the next state should be.Ambiguity is not supported in traditional LR parsing because of thedeterministic nature of the state machine.

To support ambiguity the information access process 40 extends the LRparser to permit non-determinism in the state machine, that is, in anygiven state with any given top stack symbol, more than one successorstate is permitted. This non-determinism is supported in the informationaccess process 40 with the use of a priority queue structurerepresenting multiple states under consideration by the parser. Apriority queue is a data structure that maintains a list of items sortedby a numeric score and permits efficient additions to and deletions fromthe queue. Because the parser used in the information access process 40is permitted to be simultaneously in multiple states, the parser tracksmultiple stacks, one associated with each current state. This may leadto inefficiency. However, since the multiple concurrent states tend tohave a natural “tree” structure, because typically one state transitionsto a new set of states through multiple putative transitions, themultiple stacks can be structured much more efficiently in memory usagevia a similar tree organization.

In a traditional LR parser, the state diagram can be very large even formoderate size grammars because the size of the state diagram tends togrow exponentially with the size of the grammar. This results intremendous memory usage because grammars suitable for natural languagetend to be much larger than those for a machine programming language. Inorder to improve the efficiency of the state diagrams, the informationaccess process 40 makes use of empty transitions that are known as“epsilon” transitions. The exponential increase in size occurs becausemultiple parses may lead to a common rule in the grammar, but in adeterministic state diagram, because the state representing the commonrule needs to track which of numerous possible ancestors was used, thereneeds to be one state of each possible ancestor. However, because theinformation access process 40 has expanded the LR parser to supportambiguity via support for a non-deterministic state diagram, themultiple ancestors can be tracked via the previously described priorityqueue/stack tree mechanism. Thus, a common rule can be collapsed into asingle state in the non-deterministic state diagram rather thanreplicated multiple times. In general, performing this compression in anoptimal fashion is difficult. However, a large amount of compression canbe achieved by inserting an epsilon whenever the right-hand side of agrammar rule recourses into a non-terminal. This has the effect ofcausing all occurrences of the same non-terminal in differentright-hand-sides to be collapsed in the non-deterministic state diagram.

A concern which the information access process 40 addresses is that any“left-recursion,” that is, a rule which eventually leads to itselfeither directly or after the application of other rules, will result ina set of states in the non-deterministic state diagram that can betraversed in a circular manner via epsilon transitions. This wouldresult in a potential infinite processing while parsing. In order toprevent infinite processing, if there are multiple possible epsilontransitions in series, they are reduced to a single epsilon transition.This may result in a small amount of inaccuracy in the parser, butavoids the potential for infinite processing.

The parser of the information access process 40 has also been expandedto support regular expressions on the right-hand-side of context-freegrammar rules. Regular expressions can always be expressed ascontext-free rules, but it is tedious for grammar developers to performthis manual expansion, increasing the effort required to author agrammar and the chance for human error. Implementation of this extensionwould be to compile the regular expressions into context-free rulesmechanically and integrate these rules into the larger set of grammarrules. Converting regular expressions into finite state automata throughgenerally known techniques, and then letting a new non-terminalrepresent each state in the automata can accomplish this. However, thisapproach results in great inefficiency during parsing because of thelarge number of newly created states. Also, this expansion results inparse trees which no longer correspond to the original, unexpanded,grammar, hence, increasing the amount of effort required by the grammardeveloper to identify and correct errors during development.

An alternative used by the information access process 40 is to followthe finite state automaton corresponding to a regular expression duringthe parsing as if it were part of the overall non-deterministic statediagram. The difficulty that arises is that right-hand-sides of grammarrules may correspond to both regular expressions of terminal andnon-terminal symbols in the same rule. Thus, when the LR parser of theinformation access process 40 reaches a reduce decision, there is nolonger a good one-to-one correspondence between the stack symbols andthe terminal symbols recently processed. A technique needs to beimplemented in order to find the start of the right-hand side on thestack. However, because the parser uses epsilons to mark recursions toreduce the state diagram size, the epsilons also provide useful markersto indicate on the stack when non-terminals were pursued. With thisinformation, the LR parser of the information access process 40 is ableto match the stack symbols to the terminals in the input text beingparsed.

Another efficiency of the LR parser of the information access process 40involves the ability to support “hints” in the grammar. Because naturallanguage grammars tend to have a large amount of ambiguity, andambiguity tends to result in much lengthier parsing times. In order tokeep the amount of parsing time manageable, steps must be taken to“prune” less promising putative parses. However, automatic scoring ofparses for their “promise” is non-trivial. There exist probabilistictechniques, which require training data to learn probabilities typicallyassociated with each grammar rule. The LR parser of the informationaccess process 40 uses a technique that does not require any trainingdata. A grammar developer is allowed to insert “hints,” which are eithermarkers in the grammar rules with associated “penalty costs” or“anchors.” The penalty costs permit the grammar developer to instructthe LR parser of the information access process 40 to favor certainparses over others, allowing for pruning of less-favored parses. Anchorsindicate to the LR parser that all other putative parses that have notreached an anchor should be eliminated. Anchors thus permit the grammardeveloper to specify that a given phrase has a strong likelihood ofbeing the correct parse (or interpretation), hence, all other parses arediscarded.

Another concern with supporting ambiguous grammars is that the largenumber of parses consumes much memory to represent. The LR parser of theinformation access process 40 is modified to represent a list ofalternative parse trees in a graph structure. In the graphrepresentation, two or more parse trees that share common substructurewithin the parse tree are represented as a single structure within thegraph.

The edges in the graph representation correspond to grammar rules. Agiven path through the graph represents a sequential application of aseries of grammar rules, hence, uniquely identifying a parse tree.

Once a graph representation of potential parses is generated, at the endof parsing a frame representation of the relevant potential parses isoutputted. This is achieved via a two-step method. First, the graph isconverted into a series of output directives. The output directives arespecified within the grammar by the grammar developer. Second, framegeneration occurs as instructed by the output directives. The first stepis complicated by the support for regular expressions within the grammarrules because a node in the parse tree may correspond to the applicationof a regular expression consisting of non-terminals, which in turncorresponds to application of other grammar rules with associated outputdirectives. The identity of these non-terminals is not explicitly statedin the parse tree. In order to discover these identities, during thefirst step, the process follows a procedure very similar to thepreviously described LR parser, but instead, because one already has aparse tree, the parse tree is used to “guide” the search controlstrategy. Once the proper identities are discovered, the correspondingoutput directives are sent to the second stage.

The information interface 80 frequently needs to access multiple tablesin an RDBMS in order to fulfill a data request made by the control logicof the information access process 40. It is unwieldy for the systemdeveloper to specify rules on which tables need to be accessed toretrieve the requested information. Instead, it is much simpler for thesystem developer to simply specify what information is available inwhich tables. Given this information, the information interface 80 findsthe appropriate set of tables to access, and correlates informationamong the tables. The correlation is carried out by the informationinterface 80 (of FIG. 4) requesting a standard join operation in SQL.

In order to properly identify a set of tables and their respective joincolumns, the information interface 80 (of FIG. 4) views the set oftables as nodes in a graph and the potential join columns as edges in agraph. Given this view, a standard minimum spanning tree (MST) algorithmmay be applied. However, the input to the information interface 80 is arequest based on features and not on tables. In order to identify thetables and join columns, the information interface 80 treats the set oftables as nodes in a graph and the set of join columns as edges in thegraph. A standard minimum spanning tree (MST) algorithm can be applied.One problem is that the same feature may be represented in more than onetable. Thus, there may be multiple sets of tables that can potentiallyprovide the information requested. In order to identify the optimal setof tables and join columns, the information interface 80 must apply aMST algorithm to each possible set of tables. Because the number ofpossible sets can expand exponentially, this can be a very timeconsuming process. The information interface 80 also has the ability tomake an approximation as follows. There is a subset, which may be zero,one, or more, of features, which are represented in only one table perfeature. These tables therefore are a mandatory subset of the set oftables to be accessed. In the approximation, the information interface80 first applies a MST algorithm to the mandatory subset, and thenexpands the core subset so as to include all the requested tables. Theexpansion seeks to minimize the number of additional joins needed tocover each feature not covered by the mandatory subset.

Other embodiments are within the following claims.

1. A computer-implemented method of generating a natural languageexpression in response to a query, comprising: generating a text framefrom the query; and processing the text frame in conjunction with agrammar and one or more logic configuration files applied recursively tothe text frame to generate the natural language expression from thequery, the logic configuration files including functions that can passarguments.
 2. The computer-implemented method of claim 1 furthercomprising matching the natural language expression to content residingin a database.
 3. The computer-implemented method of claim 2 in whichthe database resides in a server in a network.
 4. Thecomputer-implemented method of claim 2 in which the matched content is asearch result summary.
 5. The computer-implemented method of claim 1wherein the text frame comprises a data structure, the data structurerepresenting an expanded query, the expanded query representingdifferent elements of the query and different criteria of the query. 6.The computer-implemented method of claim 5 wherein the data structurecomprises rows, each of the rows having a key, the key identifyinginformation in each of the rows.
 7. The computer-implemented method ofclaim 6 wherein the data structure further comprises a plurality of datastructures.
 8. The computer-implemented method of claim 7 wherein thegrammar comprises natural language rules.
 9. The computer-implementedmethod of claim 7 wherein the generating the text frame furthercomprises encapsulating the processed text frame in a markup language.10. The computer-implemented method of claim 9 wherein the markuplanguage is extensible markup language (XML).
 11. Thecomputer-implemented method of claim 9 wherein the markup language ishypertext markup language (HTML).
 12. A computer-implemented method ofprocessing a query comprising: generating a text frame for the query;loading a grammar and one or more logic configuration files; andprocessing the text frame in conjunction with the grammar and the one ormore logic configuration files to generate a natural language expressionfrom the query.
 13. The computer-implemented method of claim 12 furthercomprising matching the natural language expression to content residingin a database.
 14. The computer-implemented method of claim 13 in whichthe database resides in a server in a network.
 15. Thecomputer-implemented method of claim 13 in which the matched content isa search result summary.
 16. The computer-implemented method of claim 15in which the text frame comprises a data structure, the data structurerepresenting an expanded query, the expanded query representingdifferent elements of the query and different criteria of the query. 17.The computer-implemented method of claim 16 in which the data structurecomprises rows, each of the rows having a key, the key identifyinginformation in each of the rows.
 18. The computer-implemented method ofclaim 17 in which the data structure comprises a plurality of datastructures.
 19. The computer-implemented method of claim 12 in which thegrammar comprises natural language rules.
 20. The computer-implementedmethod of claim 12 in which generating the text frame further comprisesencapsulating the processed text frame in a markup language.